1. Field of the Invention
The invention relates to a method of inspecting a secondary battery, which method can reduce the time required to inspect the secondary battery.
2. Description of Related Art
When secondary batteries, such as lithium-ion batteries, are manufactured and shipped, some initial characteristics, such as the capacity and the output or power, of the secondary batteries are checked in a pre-shipping inspection process. To check the capacity and output of a secondary battery, for example, in the pre-shipping inspection process, an activation treatment for activating the secondary battery by initially charging the battery, and a high-temperature aging treatment, are performed. After the activation treatment and the high-temperature aging treatment, the secondary battery is discharged until its voltage becomes equal to a specified voltage, and its capacity is measured. Then, the temperature and voltage (SOC: State Of Charge) of the secondary battery are suitably controlled, and the secondary battery is discharged at a specified current for a certain period of time, for measurement of the IV resistance, whereby the output of the secondary battery is measured.
In a process of manufacturing secondary batteries as described in Japanese Patent Application Publication No. 10-289729 (JP 10-289729 A), after the secondary batteries are subjected to a high-temperature aging treatment and an activation treatment, the batteries are left to stand for a given period of time (first buffering step), and then the capacity of each battery is checked. Then, after the secondary batteries are further left stand for a given period of time (second buffering step), the open-circuit voltage (OCV) is measured, and the secondary batteries are sorted out according to the current capacity value, so that selected ones of the secondary batteries are shipped.
As described above, in the pre-shipping inspection process of measuring the capacity and output of the secondary battery, the discharge for measuring the capacity and the discharge for measuring the output are separately carried out, and, therefore, a large amount of inspection time is required. Also, in the inspection process as described in JP 10-289729 A, since the secondary batteries are left to stand and the open-circuit voltage is measured, after the battery capacity is checked, the SOC and temperature of the secondary batteries need to be controlled after measurement of the capacity, and a large amount of time is required for the inspection process.